ochem question

[wait4me]

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one of the problems suggested that carboxylic acids are soluble in dilute base and amines are soluble in dilute acid....

can someone explain this and how we would know which functional groups are soluble in what conditions? i thought like dissolves like...so why is carboxylic acid soluble in base?

 

[inaccensa]

one of the problems suggested that carboxylic acids are soluble in dilute base and amines are soluble in dilute acid....

can someone explain this and how we would know which functional groups are soluble in what conditions? i thought like dissolves like...so why is carboxylic acid soluble in base?

Yes like dissolves like, but what is the definition of that? Polar substances can dissolve polar. Non-polar dissolves polar. When you have a strong acid in presence of the a weak base, it will be completely deprotonated. Deprotonating will give you carboxylate ion, which is polar. When a weak acid dissolves with a strong base, it completely protonates the base.

 

[Phosphorus Ylide]

The two examples that you mention are just simple acid/base reactions. R-COOH can donate a proton to a dilute base and R-NH2 can accept a proton from a weak acid. It's the principle that allows for a liquid/liquid extraction. If the compound was just a simple alkane, then you are right. You would want to use something pretty organic and nonpolar